<?php

/**
 * @Author: tan
 * @Date:   2019-09-27 14:28:28
 * @Last Modified by:   tan
 * @Last Modified time: 2019-09-27 14:40:29
 */
$a = 3; $b = 5;
$count = 10**8;
$st = time();
while ($count >= 1 ) {
    $count --;
    $temp = $a;
    $a = $b;
    $b = $temp;
}
$ed = time();
print_r($ed - $st);